How can i add costs such as Freight, Loading Charges to Parts (Products) while transferring to another Site from the MAIN SITE ??
First step will be to setup another costID and link that cost ID to the other site. This will allow having different costs for every part.
To add costs for freight etc. you may need to sell the parts to the other site, and receive them in through a PO. In the po receipt you can utilize landed costs. The problem with approach is now you have AR and AP to deal with.
Option two would be to do a cost adjustment on the part at the time of the receipt and add something to the material burden value.